1. Field of the Invention
The present invention relates to agricultural implements, and, more particularly, sensors for use with actuators in such implements.
2. Description of the Related Art
In the continuing quest for providing greater efficiency in the operation of farm implements, machines have been constructed to have ever increasing lateral spans relative to a tractor or central unit propelling the unit over a field. When the span increases to realize greater efficiency and speed, the criteria of having a uniform and level tool contact with the soil becomes extremely critical. Equipment with significant lateral spans has many different joints and is usually articulated to enable transport to and between fields.
An area of special importance to level positioning of farm implements is found in the tillage field. The desirable outcome is a uniform physical depth of the tillage and a uniform entry of the disk blades or harrows into the soil. The need to have a level positioning of the implement is made more challenging with the use of hydraulic actuators which control the depth of penetration of the disk blades or other tools. In current practice, hydraulic actuators are connected in series and it is possible through normal operation for hydraulic fluid leakage to make the actuators out of sync with one another.
It is current practice to counter this occurrence by fully elevating the implement to the point where bypass lands in the actuators allow full flow of hydraulic fluid to pass through the actuators and again synchronize the multiple units. However, this adds an additional step to the operation, particularly in the field, thereby decreasing the efficiency and speed with which the particular task is accomplished. It has been proposed in co-pending application entitled “Remote Leveling of Tillage Implements”, of common assignment with the present invention, to incorporate position sensors into hydraulic actuators to achieve remote leveling. With such an arrangement, the accuracy of the displacement sensors used in the system is important. Current displacement sensors are employed by fixing them at a minimum clearance from the actuator output shaft to read signals reflecting displacement of the output shaft. In the agricultural environment, the positioning of the sensor is a problem because the current practice of inserting the sensor until contact with the shaft and then backing it off may result in alteration of the sensor signal.
What is needed in the art therefore, is the accurate and safe installation of a sensor used with an agricultural implement actuator.